Masonry Magazine February 1979 Page. 29
TABLE 1. Maximum Concrete Masonry Wall Heights (Feet) between Lateral Supports
A41.1-1953 (1)
NCMA Standard (2)
Proposed ACI Standard (3)
Nominal Wall Thickness (in.) | Hollow Units | Solid Units
---|---|---
| (18t) | (20t) |
| Non-reinforced | Reinforced | Reinforced |
| Non-reinforced | All other bearing walls | bearing walls | non-bearing walls | bearing walls |
| walls | (20t) | (30t) | (36t) | (20t) | (36t)
6 | 9 | 9 | 10 | 15 | 18 | 10 | 18
8 | 12 | 13.33 | 13.33 | 20 | 24 | 13.33 | 24
10 | 15 | 16.67 | 16.67 | 25 | 30 | 16.67 | 30
12 | 18 | 20 | 20 | 30 | 36 | 20 | 36
One-story residence buildings and private garages, except height to peak of gable may be 15 feet.
(1) "American Standard Building Code Requirements for Masonry, A41,1-1953 (R 1970).
(2) "Specification for the Design and Construction of Load Bearing Concrete Masonry," NCMA, 1970
(3) "Building Code Requirements for Concrete Masonry Structures," Proposed ACI Standard, Title No. 75-42, ACI Journal, August and Sept. 1978
TABLE 2. Coefficients for Stiffened Walls
Pilaster spacing
Pilaster width
Ratio:
Pilaster spacing (o.c.)
p
23
Pilaster width
| | 6 | 8 | 10 | 15 | 20 or more |
|---|---|---|---|---|---|
| | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| | 1.4 | 1.3 | 1.2 | 1.1 | 1.0 |
| | 2.0 | 1.7 | 1.4 | 1.2 | 1.0 |
Linear Interpolation between the values of the coefficients given in the table shall be permitted but not extrapolation outside the limits given.
TABLE 3. Maximum Wall Heights for Reinforced Concrete Masonry Walls Subject to Wind**
Nominal wall Thickness (in.) | Wind Load, w (psf) | Vertical Reinforcement | 10 | 15 | 20 | 25 | 30
---|---|---|---|---|---|---|---
6 | No. 4 @ 48" | | 15.2 | 12.4 | 10.7 | 9.6 | 8.8
6 | No. 5 @ 48" | | 18.0 | 15.4 | 13.3 | 11.9 | 10.9
6 | No. 6 @ 48" | | 18.0 | 15.7 | 14.0 | 12.8 |
6 | No. 5 @ 24" | | | | 17.8 | 15.9 | 14.6
6 | No. 6 @ 24" | | | | 18.0 | 16.9 | 15.4
8 | No. 4 @ 48" | | 17.8 | 14.5 | 12.6 | 11.2 | 10.3
8 | No. 5 @ 48" | | 22.1 | 18.0 | 15.6 | 14.0 | 12.7
8 | No. 6 @ 48" | | 21.3 | 18.4 | 16.5 | 15.0 |
8 | No. 5 @ 24" | | | | 21.7 | 19.4 | 17.7
8 | No. 6 @ 24" | | | | 24.0 | 21.8 | 19.9
10 | No. 4 @ 48" | | 20.0 | 16.4 | 14.2 | 12.7 | 11.6
10 | No. 5 @ 48" | | 24.9 | 20.3 | 17.6 | 15.7 | 14.4
10 | No. 6 @ 48" | | 29.4 | 24.0 | 20.8 | 18.6 | 17.0
10 | No. 5 @ 24" | | | | 28.3 | 24.5 | 21.9
10 | No. 6 @ 24" | | | | 29.0 | 25.9 | 23.6
12 | No. 4 @ 48" | | 22.1 | 18.0 | 15.6 | 14.0 | 12.8
12 | No. 5 @ 48" | | 27.4 | 22.4 | 19.4 | 17.4 | 15.8
12 | No. 6 @ 48" | | 32.4 | 26.5 | 22.9 | 20.5 | 18.7
12 | No. 5 @ 24" | | | | 31.2 | 27.0 | 24.2
12 | No. 6 @ 24" | | | | 36.0 | 32.0 | 28.6
Maximum wall height limited to 36 ft: 18 ft for 6 in. walls; 24 ft for 8 in. walls; 30 ft for 10 in. walls, and 36 ft for 12-in. walls.
Design assumptions: (1) Vertical reinforcement located at centerline of wall; (2) 1500 x 1.33=1995 psi; (3) 20,000 x 1.33=26,667 psi; (4) total area of steel in wall is not less than 0.002 times the cross-sectional area of wall (not more than 2/3 of which is used in either direction)